Support Markdown/Notebook-Friendly Documentation Export for Downstream Integration (copy all markdown and rst files) (#18223)

docs/Makefile

@@ -41,8 +41,20 @@ compile:
 # Convert Notebook files to Markdown artifacts (no execution)
 markdown:
 	@set -e; \
-	echo "Exporting notebooks to Markdown..."; \
+	echo "Exporting docs to Markdown..."; \
 	mkdir -p "$(BUILDDIR)/html/markdown"; \
+	\
+	# 1) Copy .md and .rst files under subdirectories only (exclude root-level files) \
+	find $(SOURCEDIR) -mindepth 2 -path "*/_build/*" -prune -o \( -name "*.md" -o -name "*.rst" \) -print0 | \
+		parallel -0 -j3 --halt soon,fail=1 ' \
+		SRC="{}"; \
+		REL_DIR=$$(dirname "$$SRC"); \
+		OUT_DIR="$(BUILDDIR)/html/markdown/$$REL_DIR"; \
+		mkdir -p "$$OUT_DIR"; \
+		cp -f "$$SRC" "$$OUT_DIR/"; \
+		' || exit 1; \
+	\
+	# 2) Convert .ipynb -> .md (all notebooks, including root if any) \
 	find $(SOURCEDIR) -path "*/_build/*" -prune -o -name "*.ipynb" -print0 | \
 		parallel -0 -j3 --halt soon,fail=1 ' \
 		NB_SRC="{}"; \
@@ -56,8 +68,10 @@ markdown:
 			--output-dir "$$OUT_DIR" \
 			>/dev/null; \
 		' || exit 1; \
+	\
 	echo "Markdown artifacts written to: $(BUILDDIR)/html/markdown"
 
+
 # Serve documentation with auto-build and live reload
 serve:
 	@echo "Starting auto-build server at http://0.0.0.0:$(PORT)"